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 Post subject: 480 VAC 1200A Circuit Breaker Open/Close Operation
PostPosted: Fri May 10, 2024 8:44 am 

Joined: Fri May 10, 2024 8:26 am
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I have an enclosed unit substation consisting of a 15 kV fused primary switch. a 2500 kVA 13.8kV primary, 480/277 VAC secondary oil filled transformer, close coupled to a 4 air circuit breaker walk in switchgear unit.

Per NFPA 70E, am I required to wear PPE in order to open and close any of the circuit breakers?

Thanks.


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 Post subject: Re: 480 VAC 1200A Circuit Breaker Open/Close Operation
PostPosted: Sat May 11, 2024 7:04 pm 
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Location: Scottsdale, Arizona
This operation is considered "Interaction" and according to 2024 NFPA 70E requires an arc flash risk assessment (assuming no shock hazards)

Table 130.5(C) Estimate of the Likelihood of Occurrence of an Arc Flash Incident for ac and dc Systems.
This table lists many tasks such as “Operation of a CB, switch, contactor or starter”

For this task there is a column for “Likelihood of Occurrence” of an Arc Flash

To satisfy the “No” likelihood of occurrence for this task, the equipment must be in “Normal Operating Condition.”
NFPA 70E provides seven conditions that must be met such as the equipment is properly installed, properly maintained, no evidence of impending failure and more.

If all of these conditions can be met, then according to the table, there is “No” likelihood of occurrence of an arc flash.

Note: My usual disclaimer. Although I'm involved with many different standards, this response is a personal view and may or may not represent any official position of NPFA, IEEE etc.


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